Migrating from MMC to SD card

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Hi all,

We currently have a (client's) product that uses an MMC (SPI mode) for
datastorage, the client would like to change this to SD card.

After searching the web, I did find the SD card simplified physical
layer spec, but not much else. The www.sdcard.org site keeps giving me
timeouts. I also get the impression that I will need to become a member
before I can view any usefull stuff on that site.

From what I understand, it is possible to access an SD card as if it where
an MMC (both in SPI mode), with only a minor difference in initialization.
Is this true?

The client would also like the possiblity to change to 4-bit mode later on.
All signals will be routed through programmable logic. We will not be using
any of the security features.

Has anyone found more usefull information on the web? Any tips?

--
Stef    (remove caps, dashes and .invalid from e-mail address to reply by mail)

Everyone is more or less mad on one point.
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Re: Migrating from MMC to SD card

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You should only have to be an SD member to implement the 'secure'
stuff (which, to me, suggests that some "security by obscurity" may be
involved --- bad idea!).  I don't quite see what your client is trying
to gain by this move, though.

--
Hans-Bernhard Broeker ( snipped-for-privacy@physik.rwth-aachen.de)
Even if all the snow were burnt, ashes would remain.

Re: Migrating from MMC to SD card
In comp.arch.embedded,
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We don't need the secure stuff, so that should not be a problem. But where
would I find the complete SD spec minus secure stuff?

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Mainly for capacity reasons. They've heard SD's with 4GB are already
announced. There is also a concern for he future of MMC, which seems to
be loosing terrain.

And because SD and MMC ar physically compatible, they can keep using the
MCC and be ready for SD.

--
Stef    (remove caps, dashes and .invalid from e-mail address to reply by mail)

After all my erstwhile dear,
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Re: Migrating from MMC to SD card
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SanDisk has some publicly available documents. I'm not sure where to
find them on their site, but I know I have them archived somewhere...
if only I could find them :)

Re: Migrating from MMC to SD card
In comp.arch.embedded,
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If you mean these, I found them. ;-)
http://www.sandisk.com/oem/application-notes.asp


--
Stef    (remove caps, dashes and .invalid from e-mail address to reply by mail)

I just remembered something about a TOAD!

Re: Migrating from MMC to SD card
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No, this document is called something like SD_Architecture_1.0.pdf.
Didn't see it on that page you pointed to.

Re: Migrating from MMC to SD card
In comp.arch.embedded,
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I did also find ProdManualSDCardv1.9.pdf somewhere on the sandisk site.
This is a 113 page document that also has things like the register
definition.

This document is is also not on the above link, think I found with the
search tool.

--
Stef    (remove caps, dashes and .invalid from e-mail address to reply by mail)

There is more simplicity in the man who eats caviar on impulse than in the
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Re: Migrating from MMC to SD card
On Tue, 02 Nov 2004 00:10:29 +0000, stef33d@yahooI-N-V-A-L-I-D.com.invalid

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For anyone who's interested, the link is
http://www.sandisk.com/pdf/oem/ProdManualSDCardv1.9.pdf

MiniSD card
http://www.sandisk.com/pdf/oem/ProdManualminiSDv1.1.pdf

Older SD card specs
http://www.sandisk.com/download/Product%20Manuals/Product%20ManualSDCardv1.7.pdf

These files are hidden on the SanDisk pages.

Re: Migrating from MMC to SD card
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If your code implements the MMC spec as documented by Sandisk, it
should work with an SD card.  You don't have to do any special
initialization.  When I tested my MMC code with an SD card, the only
real "difference" I found was that SD cards tended to be slower in
responding to commands; the MMCs I was using always responded in the 8
clock cycles following the command while the SD cards had a longer
Ncr: 16 or more clock cycles.  But the MMC spec allows Ncr to be 64
clock cycles, so this is still within spec.

--
John W. Temples, III

Re: Migrating from MMC to SD card
In comp.arch.embedded,
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It's not my code, so we will have to see but this sounds very promising.

--
Stef    (remove caps, dashes and .invalid from e-mail address to reply by mail)

There's a fine line between courage and foolishness.  Too bad it's not a fence.

Re: Migrating from MMC to SD card
On Thu, 28 Oct 2004 23:58:20 +0000, stef33d@yahooI-N-V-A-L-I-D.com.invalid

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You can send some more instructions to the SD card once it is initialised, and
the SPI will speed up to 25MHz. The slower data rates are so the SD card
is compatible with the MMC card. The SD card socket is thinner I think, so that
MMC cards can't be used with it, but SD cards can be used with the MMC socket.

Contact your local Sandisk distributor, and ask for the following document:

Sandisk Secure Digital Card
Product Manual
Version 1.9 (there may be a later version than this)
Document Number 80-13-00169
December 2003

You will have to sign an NDA though to get it. Make sure that you check the
operation of cards from different manufacturers as well because they may not
have exactly the same implementation as Sandisk.

Regards
David Milne



Re: Migrating from MMC to SD card
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No, it's the other way around.

--
John W. Temples, III

Re: Migrating from MMC to SD card
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document



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